Reduction gear



G. H. ACKER REDUCTION GEAR Feb. 14, 1939.

2 Sheets-Sheet l Filed Ooi. l5, 1935 Feb. M, 193.. G. ACKER 2,147,39

REDUCTION GEAR Filed Oct. l5, 1935 2 Sheets-Sheet 2 "31%) Y@ INVENTOR. 4 56029@ #Ac/fe? ATTORNEY Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE REDUCTION GEARl George H. Acker, Shaker Heights, Ohio, assigner to The Cleveland Worm and Gear Company, Cleveland, Ohio, a corporation of Ohio The present invention relates to an improvement in the construction of reduction gear units and has particular reference to the provision of meansfor cooling the unit while in operation, and thereby dissipating the heat generated principally by gear tooth contact, and permitting a greater operating efficiency aswell as a substantial increase in power rating of the gear reduction unit.

One of the objects of my invention is to provide means for circulating a stream of cooling air about the gear unit housing in such a manner as not to interfere with the structural strength of the housing and at the same time to secure an emcient cooling air circulation with the utilization of relatively simple and economical construction. Heretofore it has been the practice to `air cool a gear reduction unit by means of fan mounted on the end of the high speed horizontal shaft, such fan being of a diameter large enough to force the air stream in a horizontal direction past the side walls of the unit housing. Such a prior construction is more fully described in my prior Patent No. 1,564,742 issued December 8, 1925. Such prior construction has been found to be disadvantageous in that, first, an air circulating fan must be employed which is large enough to throw a slip stream along the sides of the housing; and secondly, such a construction practically prevented the incorporation of Vertical reinforcing ribs in the housing. In the stronger and better constructed reduction gear unit housings, it is necessary to incorporate vertical reinforcing ribs in the side walls of the housf ing in order to properly support the load, and forces which are applied to the upper portion of the gear unit. These vertical supporting ribs in the unit housing can either be made to extend inwardly or outwardly from the sidewalls of the housing. Where the ribs extend outwardly from the housing, they of course would have the effect of baflling or breaking up a horizontally directed cooling air stream. Where the ribs are directed inwardly of the side walls of the housing, the result is that the width of the housing becomes so great as to practically and commercially prevent the use of a fan large enough to force an air stream past the side walls of the housing.

lt is an object of the present invention to overcome these disadvantages just enumerated. A further object of the invention is to obtain a more rapid and efiicient cooling effect by providing a relatively greater area of cooling air contact with the gear unit housing than has heretofore been utilized. Additional objects and advantages shall become apparent as the following description proceeds.

To the accomplishment of the foregoing andl means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and the following description set forth in detail certain mechanism embodying the invention, such disclosed means constituting, however, but one of various mechanical forms in which the principle of the invention may be used In said annexed drawingsz- Fig. l is a side elevational view with parts partially broken away of the gear reduction unit having the air cooling device constructed according to the principle of my invention; Fig. 2 is a sectional view taken upon a plane normal to that of Fig. l and substantially along line 22 thereof ,'Fig. 3 is a sectional view of the lower casting portion of the gear unit housing and taken substantially along line 3 3 of Fig. 1; Fig. 4 is a side elevational view of a reduction gear unit illustrating a modified form of the invention.

Now referring more particularly to the drawings, there is sho-wn therein a gear unit housing consisting of the lower casting portion i and the upper casting portion 2. The lower portion E of the housing carries the high speed worin shaft E? which is suitably journalled therein by means of the ball bearing fi., The interior of the lower housing l of course serves as an oil reservoir. The low speed shaft 5 carries a worm gear meshing with the worm on the high speed shaft The interior construction of the reduction gear unit, including the gears themselves, is not shown or described in greater detail herein since such construction is well known to those skilled in the art and is of course present by necessary implication in the explanation of the present invention.

On the left hand outer end of the high speed worm shaft 3, a centrifugal type air impelling fan consisting of the radial blades ii and hub l is mounted. A housing il attached to gear housing i encloses the fan blades ii, a cover plate 9, having a central opening over which the protective screen lil extends, is attached to the end of the housing ii.

Four vertical reinforcing ribs ii extend from the upper horizontal flange is of the lower housing I down to the base or feet i2 of the housing. These reinforcing ribs il are for purpose of properly supporting the weight of the upper porn tion 2 of the gear unit as well as for imparting sufficient strength and rigidity to the housing in order to withstand the torque and forces which are applied to the low speed shaft The bottom wall I3 of the housing i is raised from the base line upon which the feet it rest and thereby together with the side walls it and it extending below the bottom wall iii, define a space it. As will be noted in Fig. l, the left hand end wall Il of the housing l does not extend to the base thereof, thereby leaving an opening from the space I4 underneath the bottom Wall I3 to the passage I8 leading from the chamber defined by the fan housing 8. Spaced at intervals between the reinforcing ribs I I are the heat dissipating fins 20 and 2l extending outwardly from the side Walls I5 and I 6. It will be noted that the fins 20 terminate at a point above the lower ends of the fins 2I and that the upper ends of the latter terminate at a point below the ends of the former, thus defining a circuitous passage as indicated by the arrows in Fig. 1. Those portions of the side walls I5 and I5 of the housing I which extend below the bottom I5 are cut away adjacent the space defined by the right hand ribs II and the first of the series of fins 2i. Thus the openings 22 and 23 in the side walls I5 and I5 respectively place the bottom space III in communication with one end of the circuitous passage defined by the fins 20 and ZI Cover plates 24 and 25 extend over the outside lateral edges of the fins 20 and 2| and are secured by means of suitable fastening studs 2G to the reinforcing ribs II. Thus the circuitous passage defined by the ribs 20 and 2| is wholly enclosed in order to confine the air stream travelling therethrough. The cover plates 24 and 25 have a portion removed as at 21 adjacent the upper end of the space defined by the left hand reinforcing ribs II and the first of the series of fins 20 adjacent thereto, whereby an exhaust opening 28 is provided at the end of the circuitous passage. In this manner, during operation of the unit, air is drawn in through the screen I0, forced by the fan blades 6 through the passage I8 to the space I4, through the openings 22 and 23 and thence along the circuitous passage, (on each side wall I5 and I 6) defined by the fins 20 and 2 I, and out through the exhaust openings 28. Heat generated by the .operation of the reduction gears and transmitted to the housing, mainly through the lubricant contained therein is thus dissipated by the passage of cooling air not only past the side walls I5 and I 6, but also along the bottom wall I3. A proper control of the temperature of operation of the gear reduction unit is thus maintained, as well as permitting the unit to transmit a greater amount of power for its size than would be the case in the event that the generated heat were not thus dissipated.

Although I have shown an impeller or centrifugal type of fan 6, it will be readily appreciated by those skilled in the art that any other type of air propelling means such as a propeller blade fan may be substituted therefor. It should also be noted that a relatively smaller size of fan is employed than that heretofore used, since it is not necessary that the slip stream therefrom extend over an area greater than the width of the gear unit housing. In fact, as will be seen from the drawings, the diameter of fan 6 is less than the distance between the outer edges of the ribs II on opposite sides of the housing I.

In Fig. 4 I have shown an alternative form of construction of the heat dissipating ns on the side walls of the housing I. The lower ends of the fins 30 terminate at the bottom wall I3 of the housing and the spaces defined by the fins are each in communication with the space III under the bottom wall I3 by reason of the fact that portions of the side walls I5 and I6 extending below the bottom wall I3 and between the end walls I1 and I'I' have been removed, as indicated at 3|. The upper edge of the cover plate 33 terminates short of the upper ends of the fins 30 in order to leave a series of exhaust openings 34 at each upper end of the spaces defined by the fins. In this manner the air which is circulated through the spaces dened by the ns 30, the side walls I5 and I6 of the housing I and the cover plate 33 makes but a single vertical pass from the bottom to the top, rather than a series of up and down passes through the circuitous passage as previously described. The above described construction possesses the advantageous feature in that the forced circulation of air is in aid of the natural convection currents travelling from the bottom to the top of the housing.

It will be noted from the drawings that the cover plates 24 and 25, the side walls I5 and I6, and the end wall I'I' do not extend as far down as the plane of the mounting feet I2, leaving a slight clearance space. This form of construction is merely a matter of convenient manufacturing practice, since it is necessary to machine the bottom faces of the mounting feet I2 to obtain an accurate mounting, and it is not feasible to machine the relatively thin walled cover plates and side walls. The slight clearance space which results has a negligible effect on the escape of air from beneath the housing.

Other 'modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanisrn herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:-

l. In a reduction gear unit, the combination of a gear housing having vertical reinforcing ribs extending outwardly beyond the walls thereof, a horizontal shaft journalled in said housing, air propelling means carried by said shaft externally of said housing, a series of vertically disposed ns extending from the side walls of said housing between said reinforcing ribs, the upper and lower ends of adjacent ns being staggered with respect to each other, the end spaces between alternate fins being closed whereby to dene a circuitous passage, cover plates overlying the outer lateral edges of said fins, and means for directing the air stream from said air propelling means along the circuitous passage dei-ined by said fins.

2. In a reduction gear unit, the combination of a gear housing having vertical reinforcing ribs extending outwardly beyond the walls thereof, a horizontal shaft journalled in said housing, air propelling means carried by said shaft externally of said housing, an air passage leading the air. stream from said air propelling means to a space under the bottom of said housing, a series of vertically disposed ns extending from the side walls of said housing between said reinforcing ribs, the upper and lower ends of adjacent ns being staggered with respect to each other, the end spaces between alternate fins being closed whereby to define a circuitous passage, cover plates overlying the outer lateral edges of said fins, one end of said circuitous passage communicating with said space under the bottom of said housing, and a portion of said cover plates adjacent the other end of said circuitous passage being removed whereby said other end of said circuitous passage is open to the atmosphere.

GEORGE H. ACKER. 

